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xfs: clean up the initial read logic in xfs_readsb

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The initial sb read is always for a device logical block size buffer.
The device logical block size is provided in the bt_logical_sectorsize in
struct buftarg, so use that instead of the confusingly named
xfs_getsize_buftarg buffer that reads it from the bdev.

Update the comments surrounding the code to better describe what is going
on.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Carlos Maiolino <cem@kernel.org>
This commit is contained in:
Christoph Hellwig 2025-07-07 14:53:12 +02:00 committed by Carlos Maiolino
parent f2eb2796b9
commit a578a8efa7
2 changed files with 11 additions and 11 deletions
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1
fs/xfs/xfs_buf.h
View File

@ -375,7 +375,6 @@ extern void xfs_buftarg_wait(struct xfs_buftarg *);
extern void xfs_buftarg_drain(struct xfs_buftarg *);
int xfs_configure_buftarg(struct xfs_buftarg *btp, unsigned int sectorsize);
#define xfs_getsize_buftarg(buftarg) block_size((buftarg)->bt_bdev)
#define xfs_readonly_buftarg(buftarg) bdev_read_only((buftarg)->bt_bdev)
int xfs_buf_reverify(struct xfs_buf *bp, const struct xfs_buf_ops *ops);

21
fs/xfs/xfs_mount.c
View File

@ -171,19 +171,16 @@ xfs_readsb(
ASSERT(mp->m_ddev_targp != NULL);
/*
* For the initial read, we must guess at the sector
* size based on the block device. It's enough to
* get the sb_sectsize out of the superblock and
* then reread with the proper length.
* We don't verify it yet, because it may not be complete.
* In the first pass, use the device sector size to just read enough
* of the superblock to extract the XFS sector size.
*
* The device sector size must be smaller than or equal to the XFS
* sector size and thus we can always read the superblock. Once we know
* the XFS sector size, re-read it and run the buffer verifier.
*/
sector_size = xfs_getsize_buftarg(mp->m_ddev_targp);
sector_size = mp->m_ddev_targp->bt_logical_sectorsize;
buf_ops = NULL;
/*
* Allocate a (locked) buffer to hold the superblock. This will be kept
* around at all times to optimize access to the superblock.
*/
reread:
error = xfs_buf_read_uncached(mp->m_ddev_targp, XFS_SB_DADDR,
BTOBB(sector_size), &bp, buf_ops);
@ -247,6 +244,10 @@ xfs_readsb(
/* no need to be quiet anymore, so reset the buf ops */
bp->b_ops = &xfs_sb_buf_ops;
/*
* Keep a pointer of the sb buffer around instead of caching it in the
* buffer cache because we access it frequently.
*/
mp->m_sb_bp = bp;
xfs_buf_unlock(bp);
return 0;